This game can't go on forever, you can take from the rich and give to an increasing number of poor and not expect the poor to share the cost of goverment. At some point you cross the line of diminishing returns and "the rich" will give up as most of their wealth will be spent or taken. Then what? i don't think this reasoning is correct. "the rich" are in no danger of losing their wealth because they are not taxed on their wealth, but only on their increase.
someone will say, well what about property tax and estate tax? and i agree, these are unfair.
Well, once they start not producing income, where does that leave you? You must start taking their wealth through a "wealth tax" or eventually through inheritance taxes. Of course the entire premise is that its "not fair" that they have it to begin with.
But going back to taxes, becoming rich and taking care of yourself are things that make people want to work harder. If you take away they benefit of hard work through higher income, less and less people will if fact become "rich", and place that burden on the rest of the "non-rich".